A water trough has an isosceles triangular cross section that is 40 m across the top and 15 m deep. The trough is 2 m long. It is being filled at a rate of 0.4 m3/minute. How fast does the water level rise when the deepest point is 1 m deep? Enter your answer rounded to 3 decimal places. Do not enter units in your answer. *I entered this question before but the answer given was inaccurate. The correct answer is 0.075, but I need help with how to get that answer please. Thank you in advance.

A water trough has an isosceles triangular cross section that is 40 m across the top and 15 m deep. The trough is 2 m long. It is being filled at a rate of 0.4 m³/minute. How fast does the water level rise when the deepest point is 1 m deep? Enter your answer rounded to 3 decimal places. Do not enter units in your answer.

*I entered this question before but the answer given was inaccurate. The correct answer is 0.075, but I need help with how to get that answer please. Thank you in advance.